ananyo writes: "Prions are best known as the infectious agents that cause ‘mad cow’ disease and the human versions of it, such as variant Creutzfeldt–Jakob Disease. But as slashdot noted in 2010, the proteins also have at least one known useful function, in the cells that insulate nerves, and are suspected to have more. Now researchers have provided the first direct evidence that the proteins play an important role in neurons themselves.The team reports that prions are involved in developmental plasticity, the process by which the structure and function of neurons in the growing brain is shaped by experience, and also crucial for learning and memory."